Electrosurgical devices use electrical energy, most commonly radiofrequency (“RF”) energy, to cut tissue and/or cauterize blood vessels. During use, a voltage gradient is created at the tip of the device, thereby, inducing current flow and related thermal energy generation in the tissue. With appropriate levels of electrical energy, the thermal energy generated is sufficient to cut or shrink the tissue being treated, or cauterize blood vessels.
Existing electrosurgical devices can cause the temperature of the tissue being treated (e.g., the tissue treatment zone) to rise significantly higher than 100 degrees C., resulting in tissue desiccation, tissue sticking to the electrodes, tissue perforation, char formation and/or smoke generation. Peak tissue temperatures as a result of RF treatment can be as high as 350 degrees C., and such high temperatures may be transmitted to adjacent tissue via thermal diffusion. Undesirable results of such transmission to adjacent tissue include unintended thermal damage to the tissue. To reduce these undesirable results, electrosurgical devices have been developed that simultaneously introduce a fluid (e.g., an electrolytic solution with RF applications) to the tissue treatment zone, thereby, distributing the thermal energy at the tissue treatment zone, and providing cooling as well.
In many applications, it is often desirable to allow the surgeon or operator of the electrosurgical device to control the dimensional changes of the tissue being treated. Typically, this is accomplished by monitoring the temperature at or near the tissue treatment zone. With some electrosurgical devices, the surgeon or operator can manually control the thermal energy being introduced to the tissue treatment zone. Alternatively, other electrosurgical devices can be configured to operate with a feedback control system to automatically control the thermal energy introduced to the tissue being treated. In either case, shortcomings with existing electrosurgical devices limit their effectiveness in controlling the dimensional changes of the tissue being treated.
In particular, existing electrosurgical devices monitor the temperature at or near the tissue treatment zone using a temperature sensor, such as, a thermocouple, thermistor, phosphor-coated optical fibers, or some other temperature sensor. Various factors often influence the temperature read by the temperature sensor including the temperature of the tissue being treated as well as any fluid being simultaneously infused at the tissue treatment zone. Furthermore, the temperature being read by the temperature sensor varies as the surgeon or operator moves the electrosurgical device into or out of the tissue treatment zone. As a result of these and other factors, it is often difficult to precisely achieve the desired dimensional change (e.g., the amount of shrinkage) of the tissue being treated.
Improvements in electrosurgical devices used in surgical procedures are, therefore, sought.